John Knoll (born October 6, 1962) is an American visual effects supervisor and chief creative officer (CCO) at Industrial Light & Magic (ILM). One of the original creators of Adobe Photoshop (along with his brother, Thomas Knoll).
Thomas Knoll (born April 14, 1960) is an American software engineer who co-created Adobe Photoshop.
Little did they know back then, that together they would create a software application that would forever change the way the world creates design, photography, and art. Without them, this certainly would be an empty room right now, and the visual aspects of the communication age would be vastly different, and certainly much less exciting and dramatic than it is today.
It was Thomas Knoll who took his high-school hobby of photography, (where he learned the art of color, balance, and contrast in his father’s basement darkroom), and turned it into a program that now touches millions of lives every day.
Photoshop was developed in 1987 by two brothers Thomas and John Knoll, who sold the distribution license to Adobe Systems Incorporated in 1988. Thomas Knoll, a Ph.D. student at the University of Michigan, began writing a program on his Macintosh Plus to display grayscale images on a monochrome display.
This program (at that time called Display) caught the attention of his brother John, an Industrial Light & Magic employee, who recommended that Thomas turn it into a full-fledged image editing program. Thomas took a six-month break from his studies in 1988 to collaborate with his brother on the program.
Thomas renamed the program ImagePro, but the name was already taken. Later that year, Thomas renamed his program Photoshop and worked out a short-term deal with scanner manufacturer Barneyscan to distribute copies of the program with a slide scanner; a "total of about 200 copies of Photoshop were shipped" this way.
During this time, John traveled to Silicon Valley and gave a demonstration of the program to engineers at Apple and Russell Brown, art director at Adobe. Both showings were successful, and Adobe decided to purchase the license to distribute in September 1988. While John worked on plug-ins in California, Thomas remained in Ann Arbor writing code. Photoshop 1.0 was released on February 19, 1990 for Macintosh exclusively.
The Barneyscan version included advanced color editing features that were stripped from the first Adobe shipped version. The handling of color slowly improved with each release from Adobe and Photoshop quickly became the industry standard in digital color editing. At the time Photoshop 1.0 was released, digital retouching on dedicated high-end systems (such as the Scitex) cost around $300 an hour for basic photo retouching. The list price of Photoshop 1.0 for Macintosh in 1990 was $895.
Photoshop can edit and compose raster images in multiple layers and supports masks, alpha compositing and several color models including RGB, CMYK, CIELAB, spot color, and duotone.
Photoshop uses its own PSD and PSB file formats to support these features. In addition to raster graphics, Photoshop has limited abilities to edit or render text and vector graphics (especially through clipping path for the latter), as well as 3D graphics and video. Its feature set can be expanded by plug-ins; programs developed and distributed independently of Photoshop that run inside it and offer new or enhanced features.
According to en.wikipedia & photoshophalloffame.com